Pneumatic Tire and Method of Manufacturing the Same

ABSTRACT

To provide a pneumatic tire that can prevent photoluminescent material from falling off and can maintain visibility and fashionability based on the photoluminescent material over a long period of time when providing a decorative portion decorated with a photoluminescent material in a tire side wall and a method for manufacturing the same. The pneumatic tire of the present technology is a pneumatic tire including a decorative portion in a tire side wall decorated with a photoluminescent material, wherein at least one recess is formed in the decorative portion and the photoluminescent material is adhered within the recess.

RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.13/851,238, filed on Mar. 27, 2013, which claims priority to JapanPatent Application Serial No. 2012-71807 filed on Mar. 27, 2012.

BACKGROUND OF THE TECHNOLOGY

The present technology relates to a pneumatic tire including adecorative portion decorated with a photoluminescent material in a tireside wall and a method for manufacturing the same, and more specificallyrelates to a pneumatic tire that can prevent the photoluminescentmaterial from falling off and can maintain visibility and fashionabilitybased on the photoluminescent material over a long period of time and amethod for manufacturing the same.

Proposals concerning a pneumatic tire have been made for the purpose ofimproving visibility and fashionability by covering an outer surface ofa tire (for example, a side wall portion) with a coating material,coloring agent, or the like (see, for example, Japanese UnexaminedUtility Model Application Publication No. H7-37713 and JapaneseUnexamined Patent Application Publication (translation of PCTapplication) No. 2004-526814), and by forming a side wall portion of atire using a rubber composition that blends phosphors, ultramarine, orthe like (see, for example, Japanese Unexamined Patent ApplicationPublication No. 2000-185528A, Japanese Unexamined Patent ApplicationPublication No. 2008-174639A, and Japanese Unexamined Patent ApplicationPublication (translation of PCT application) No. 2009-538768).

However, with the method of simply applying a coating material, acoloring agent, or the like on to the outer surface of the tire, thereis a problem in that scratches are formed in a colored portion or thecolored portion falls off when the tire contacts an object such as acurb or the like.

Meanwhile, with the method of blending phosphors, ultramarine, or thelike into the rubber composition constituting the tire, there is aproblem in that an effect of improving visibility and fashionability maybe insufficient due to the existence of other additives such as carbonblack blended into the rubber composition.

SUMMARY OF THE TECHNOLOGY

The present technology provides a pneumatic tire that can prevent aphotoluminescent material from falling off and can maintain visibilityand fashionability based on the photoluminescent material over a longperiod of time when providing a decorative portion decorated with thephotoluminescent material in a tire side wall and a method formanufacturing the same.

The pneumatic tire of the present technology is a pneumatic tireincluding a decorative portion decorated with a photoluminescentmaterial in a tire side wall, wherein at least one recess is formed inthe decorative portion, and the photoluminescent material is adheredwithin the recess.

A method for manufacturing the pneumatic tire of the present technologyis a method for manufacturing the pneumatic tire including vulcanizingthe pneumatic tire including the decorative portion in the tire sidewall, the decorative portion having the recess, and adhering thephotoluminescent material to the decorative portion having the recess.

In the present technology, when providing the decorative portiondecorated with the photoluminescent material in the tire side wall, atleast one recess is formed in the decorative portion, and thephotoluminescent material is adhered within the recess to therebyprevent the photoluminescent material from falling off when the tirecontacts an object such as a curb or the like. Further, because thephotoluminescent material is adhered within the recess, scratchdurability and weatherability of the photoluminescent material can alsobe improved. Therefore, the visibility and fashionability based on thephotoluminescent material can be maintained over a long period of time.Furthermore, the recess has a larger surface area than a flat area,thereby enabling a greater amount of photoluminescent material to beadhered and to diversify the orientation of the photoluminescentmaterial; therefore, visibility and fashionability based on thephotoluminescent material can be further increased to thereby enable asecondary effect.

In the present technology, although the recess can be configured from agroove or a dimple, a groove particularly allows the photoluminescentmaterial to simply and cleanly adhere within the recess. In either case,a depth of the recess is preferably not less than 0.2 mm and not morethan 2 mm. By this, the effect of preventing the photoluminescentmaterial from falling off, visibility and fashionability can be achievedsimultaneously.

Preferably, the recess has an inclined face that inclines relative to anormal line direction of the tire surface, and a ratio of a length ofthe photoluminescent material to a width of the inclined face of therecess is from 0.3 to 0.95. Further, preferably, the recess has a bottomsurface parallel to the tire surface, and a ratio of the length of thephotoluminescent material to a width of the bottom surface of the recessis from 0.3 to 0.95. By this, the effect of preventing thephotoluminescent material from falling off, visibility andfashionability can be achieved simultaneously.

Further, it is preferred that a small protrusion be provided at aposition above a maximum depth portion of the recess, protruding intothe recess. By this, the effect of preventing the photoluminescentmaterial from falling off can be further increased.

When manufacturing the pneumatic tire described above, the pneumatictire including the decorative portion having the recess in the tire sidewall may be vulcanized and the photoluminescent material may be adheredto the decorative portion having the recess. It is particularlypreferred that the photoluminescent material be bonded to the decorativeportion having the recess using an adhesive.

In the method for manufacturing this type of pneumatic tire, it ispreferred that the photoluminescent material be compression bonded tothe decorative portion using a rigid body after the adhering of thephotoluminescent material to the decorative portion having the recess.By this, the adhered state of the photoluminescent material can beimproved.

Further, in the method for manufacturing the pneumatic tire, it ispreferred that buffing be performed for the decorative portion after theadhering of the photoluminescent material to the decorative portionhaving the recess, and the photoluminescent material that has adhered tosites away from the recess of the decorative portion is removed. Becausethe photoluminescent material that has adhered to sites away from therecess of the decorative portion is easily removed, removing this inadvance allows the photoluminescent material to maintain a stable stateover a long period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cross-sectional view illustrating the main partsof a pneumatic tire according to an embodiment of the presenttechnology.

FIG. 2 is a perspective cross-sectional view illustrating one example ofa decorative portion in the pneumatic tire according to the presenttechnology.

FIG. 3 is a perspective cross-sectional view illustrating a modifiedexample of a decorative portion in the pneumatic tire according to thepresent technology.

FIG. 4 is a perspective cross-sectional view illustrating anothermodified example of a decorative portion in the pneumatic tire accordingto the present technology.

FIG. 5 is a cross-sectional view illustrating a dimensional relationshipof the decorative portion in the pneumatic tire according to the presenttechnology.

FIG. 6 is a cross-sectional view illustrating one example of a recessformed in the decorative portion of the pneumatic tire according to thepresent technology and a small protrusion formed in the recess.

FIG. 7 is a cross-sectional view illustrating a modified example of arecess formed in the decorative portion of the pneumatic tire accordingto the present technology and a small protrusion formed in the recess.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Detailed descriptions will be given below of a configuration of thepresent technology with reference to the accompanying drawings. FIG. 1illustrates a pneumatic tire according to an embodiment of the presenttechnology.

As illustrated in FIG. 1, the pneumatic tire of this embodiment includesa tread portion 1, a pair of side wall portions 2 disposed on both sidesof the tread portion 1, and a pair of bead portions 3 disposed inward ina tire radial direction of the side wall portions 2. A carcass layer 4is mounted between the pair of bead portions 3, 3. The carcass layer 4is folded back around a bead core 5 disposed in each of the beadportions 3 from the tire inner side to the tire outer side. On the otherhand, a plurality of layers of a belt layer 6 is embedded on an outercircumferential side of the carcass layer 4 in the tread portion 1.

In the pneumatic tire, a band-like decorative portion 11 that extends inthe tire circumferential direction is formed in a tire side wall 10(outer surface of the side wall portion 2 or the bead portion 3) for thepurpose of improving visibility and fashionability. The decorativeportion 11 may include a markings 12 constituted by letters, numbers,symbols, emblems, and the like, or it may be a simple pattern that doesnot include the markings 12. A plurality of recesses 13 is formed in thedecorative portion 11, and a photoluminescent material 20 is adheredwithin the recesses 13.

FIG. 2 to FIG. 4 respectively illustrate a decorative portion in thepneumatic tire according to the present technology. In FIG. 2, aplurality of ridges 14 that protrude from the tire surface are formed onthe decorative portion 11 so as to mutually extend in parallel, and therecesses 13 constituted by grooves are formed between the ridges 14.Although the recesses 13 constituted by grooves are formed here betweenthe ridges 14 that protrude from the tire surface, the plurality ofrecesses 13 constituted by grooves that are recessed from the tiresurface may be formed so as to mutually extend in parallel such that theridges 14 remain between the recesses 13. The lateral cross-sectionalshape of the ridges 14 forms a trapezoid, and the lateralcross-sectional shape of the recesses 13 constituted by grooves forms aninverted trapezoid. In addition, the photoluminescent material 20 isadhered within the recesses 13 constituted by grooves. Further, asillustrated in FIG. 3, the lateral cross-sectional shape of the ridges14 may form a triangle, and the lateral cross-sectional shape of therecesses 13 constituted by grooves may form an inverted triangle.

In FIG. 4, a honeycomb-shape protrusion 15 that protrudes from the tiresurface is formed on the decorative portion 11, and recesses 13constituted by dimples are formed between the honeycomb-shapeprotrusions 15. Although the recesses 13 constituted by dimples areformed here between the honeycomb-shape protrusion 15 that protrudesfrom the tire surface, the plurality of recesses 13 constituted bydimples that recessed from the tire surface may be formed such that thehoneycomb-shape protrusion 15 remains between the recesses 13. Thehoneycomb-shape protrusion 15 has a lateral cross-sectional shape of thehoneycomb portion that forms a trapezoid, and the recesses 13constituted by dimples has a lateral cross-sectional shape that forms aninverted trapezoid. In addition, the photoluminescent material 20 isadhered within the recesses 13 constituted by dimples.

As the photoluminescent material 20, small pieces for a thin plate shapeor a scaled leaf shape having a length of from 50 μm to 1500 μm may beused. This type of small piece easily follows the deformation of thetire surface according to the rolling motion of the tire, and as such,is difficult to fall off. Examples of specific material includepolyethylene terephthalate (PET), aluminum, mica, talc, and the like.These materials have a high photoluminescence.

In the pneumatic tire described above, when providing the decorativeportion 11 decorated with the photoluminescent material 20 in the tireside wall 10, the plurality of recesses 13 is formed in the decorativeportion 11, and the photoluminescent material 20 is adhered within therecesses 13, and therefore, the photoluminescent material 20 can beprevented from falling off when the tire contacts an object such as acurb. Further, because the photoluminescent material 20 is adheredwithin the recesses 13, the scratch durability and weatherability of thephotoluminescent material 20 can also be improved. Therefore, thevisibility and fashionability based on the photoluminescent material 20can be maintained over a long period of time. Furthermore, the recess 13has a larger surface area than a flat area, thereby enabling a greateramount of the photoluminescent material 20 to be adhered. In addition,the photoluminescent material 20 is oriented in various directionsaccording to the inclined direction of the inner surface of the recess13 so as to provide a sheen having a stereoscopic effect, and therefore,the visibility and fashionability based on the photoluminescent material20 is further increased.

FIG. 5 illustrates a dimensional relationship of the decorative portionin the pneumatic tire according to the present technology. A depth D ofthe recess 13 is preferred to be not less than 0.2 mm and not more than2 mm, and particularly for a pneumatic tire for a passenger car, it ispreferred to be not less than 0.2 mm and not more than 1.5 mm. By this,the effect of preventing the photoluminescent material 20 from fallingoff, visibility and fashionability can be achieved simultaneously. Whenthe depth D of the recess 13 falls below the lower limit value, theeffect of preventing the photoluminescent material 20 from falling offis reduced, and conversely, when exceeding the upper limit value, thephotoluminescent material 20 is buried and visibility is reduced. Inaddition, when providing the ridge 14, there is a problem in that theridge 14 becomes easy to tear off when the depth D of the recess 13exceeds the upper limit value.

A pitch P of the recess 13 is preferred to be not more than 3 mm, andparticularly for a pneumatic tire for a passenger car, it is preferredto be not more than 2.0 mm. By this, the effect of preventing thephotoluminescent material 20 from falling off can be made appropriate.When the pitch P of the recess 13 exceeds the upper limit value, theeffect of preventing the photoluminescent material 20 from falling offis reduced.

When the recess 13 has an inclined face 13a that inclines to a normalline direction of the tire surface S, a ratio (A/B) of a length A of thephotoluminescent material 20 to a width B of the inclined face 13 a ofthe recess 13 is preferably in a range from 0.3 to 0.95. Further, whenthe recess 13 has a bottom surface 13 b that is parallel to the tiresurface S, a ratio (A/C) of the length A of the photoluminescentmaterial 20 to a width C of the bottom surface 13 b of the recess 13 ispreferably in a range from 0.3 to 0.95. By this, the effect ofpreventing the photoluminescent material 20 from falling off, visibilityand fashionability can be achieved simultaneously. When the ratio (A/B)or the ratio (A/C) is below 0.3, the photoluminescent material 20 is toosmall and visibility is reduced, and conversely, when the ratio (A/B) orthe ratio (A/C) exceeds 0.95, the photoluminescent material 20 becomesdifficult to enter the bottom side of the recess 13, and thus, theeffect of preventing the photoluminescent material 20 from falling offis reduced.

FIG. 6 and FIG. 7 are respectively cross-sectional views illustrating arecess formed in the decorative portion of the pneumatic tire accordingto the present technology and a small protrusion formed in the recess.In FIG. 6 and FIG. 7, the small protrusion 16 is formed at a positionabove a maximum depth portion of the recess 13, protruding into therecess 13. The cross-sectional shape of the small protrusion 16 is notparticularly limited and may contiguously extend along the tire surfaceor it may intermittently extend along the tire surface.

When this type of small protrusion 16 is formed in the recess 13, asillustrated in FIG. 6 and FIG. 7, the photoluminescent material 20 thathas adhered to the bottom side of the recess 13 is locked by the smallprotrusion 16, and therefore, the effect of preventing thephotoluminescent material 20 from falling off can be further increased.Of course, scratches due to fine gravel or the like and peeling due towind and rain can be effectively prevented. Note that the protrudingheight of the small protrusion 16 from the inner surface of the recess13 is preferably not more than 1.5 mm. If the protruding height of thesmall protrusion 16 is too high, the luminescent effect of thephotoluminescent material 20 is blocked.

When manufacturing the pneumatic tire described above, after thepneumatic tire provided with the decorative portion 11 having the recess13 in the tire side wall 10 has been vulcanized, the photoluminescentmaterial 20 is adhered to the decorative portion 11 having the recess13. By this, the pneumatic tire described above can be obtained.

In the method for manufacturing this type of pneumatic tire, it ispreferred that the photoluminescent material 20 be compression bonded tothe decorative portion 11 using a rigid body after the adhering of thephotoluminescent material 20 to the decorative portion 11 having therecess 13. By this, the adhered state of the photoluminescent material20 can be improved. Note that, a rigid body having a shape that conformsto the inner surface shape of the recess 13 is preferred so as tocontact with the inner surface of the recess 13. For example, in thecase of the recess 13 constituted by grooves such as that illustrated inFIG. 2 and FIG. 3, use of a disk shaped roller that conforms to thegrooves allows the work of compression bonding to be performed simply.

Further, in the method for manufacturing the pneumatic tire, it ispreferred that buffing be performed for the decorative portion 11 afterthe adhering of the photoluminescent material 20 to the decorativeportion 11 having the recess 13, and the photoluminescent material 20that has adhered to sites away from the recess 13 of the decorativeportion 11 is removed. In other words, when adhering thephotoluminescent material 20 to the decorative portion 11 having arecess 13, photoluminescent material 20 is also adhered to sites thatare away from the recess 13 of the decorative portion 11. It isacceptable for the photoluminescent material 20 to adhere excessively inthis manner. However, because the photoluminescent material 20 that hasadhered to sites away from the recess 13 of the decorative portion 11 iseasily removed, removing this in advance allows the photoluminescentmaterial 20 to maintain a stable state over a long period of time.Furthermore, when the photoluminescent material 20 that has adhered tosites away from the recess 13 of the decorative portion 11 is removed,the appearance of the decorative portion 11 is improved.

In the present technology, although adhesion of the photoluminescentmaterial 20 within the recess 13 is required, more specifically, bondingthe photoluminescent material 20 within the recess 13 is desired. Forexample, the photoluminescent material 20 may be blended into a liquidor gel form of adhesive having an adhesive strength, and the adhesivecontaining the photoluminescent material 20 can be applied to thedecorative portion 11 having a recess 13. Alternately, the adhesive maybe applied in advance to the decorative portion 11 having the recess 13and the photoluminescent material 20 can be adhered on the layer ofadhesive.

Examples

For a pneumatic tire having a tire size of 195/65R15 provided with adecorative portion in a tire side wall, a plurality of recesses made upof grooves were formed so as to extend mutually parallel in thedecorative portion as illustrated in FIG. 2, and a photoluminescentmaterial was bonded within the recesses, and a depth D of the recesses,a pitch P of the recesses, a ratio (AB) of a length A of thephotoluminescent material to a width B of an inclined face of therecess, a ratio (A/C) of the length A of the photoluminescent materialto a width C of a bottom surface of the recess, and the presence/absenceof a small protrusion within the recess were set as shown in Table 1 toproduce tires of Working Examples 1 to 6. Furthermore, a tire ofComparative Example 1 had the same structure as those in WorkingExamples 1 to 6 other than the photoluminescent material was bondedusing an adhesive to a flat decorative portion without forming recessesin the decorative portion.

As the photoluminescent material, small pieces having a scaled leafshape formed from polyethylene terephthalate were used, and thedimensions thereof were appropriately selected according to thedimensions of the recess.

The appearance of the decorative portion for these tests tires wasevaluated according to the following evaluation method and the resultswere shown in Table 1.

Appearance:

The test tires were mounted on test vehicles and the appearance of thetire surface before driving was judged by the following judgmentcriteria according to a visual inspection by 10 panelists respectively.Further, three months of road testing was performed, and the appearanceof the tire surface after driving was judged in a similar manner. Forthe evaluation results, the sum of the evaluated values based on thebelow judgment criteria was found; A is when the value is in the rangefrom 36 to 40, B is when the value is in the range from 26 to 35, C iswhen the value is in the range from 16 to 25, and D is when the value isin the range from 10 to 15.

Judgment Criteria

-   4: Gives a strong sense of sparkling-   3: Gives a sense of sparkling-   2: Gives a slight sense of sparkling-   1: Gives almost no sense of sparkling

TABLE 1 Working Working Working Working Working Working ComparativeExample Example Example Example Example Example Example 1 1 2 3 4 5 6Depth D of the — 0.2 1.5 1.0 1.0 1.0 1.0 recess (mm) Pitch P of the —2.0 2.0 2.0 2.0 2.0 2.0 recess (mm) A/B — 0.5 0.5 0.5 0.3 0.95 0.5 A/C —0.5 0.5 0.5 0.3 0.95 0.5 Presence/absence Absent Absent Absent AbsentAbsent Absent Present of a small protrusion in the recess Appearance B AA A A A A before driving Appearance after D B B B B B A driving

As is evident from Table 1, the tires of Working Examples 1 to 6, havinga plurality of recesses formed in the decorative portion and havingphotoluminescent material adhered within these recesses, had littlephotoluminescent material fall off after driving and had an excellentappearance after driving compared to Comparative Example 1. Further, thetires of Working Examples 1 to 6 also had an excellent appearance beforedriving compared to Comparative Example 1.

1. A method for manufacturing a pneumatic tire comprising a decorativeportion in a tire side wall, the decorative portion being decorated witha reflective material, wherein at least one recess is formed in thedecorative portion, and the reflective material is adhered within the atleast one recess; the method comprising: vulcanizing the pneumatic tirecomprising the decorative portion in the tire side wall, the decorativeportion having the at least one recess, and adhering the reflectivematerial to the decorative portion having the at least one recess. 2.The method for manufacturing the pneumatic tire according to claim 1,comprising: compression bonding the reflective material to thedecorative portion using a rigid body after the adhering of thereflective material to the decorative portion having the at least onerecess.
 3. The method for manufacturing the pneumatic tire according toclaim 1, comprising buffing the decorative portion after the adhering ofthe reflective material to the decorative portion having the at leastone recess, and removing the reflective material that has adhered tosites away from the at least one recess of the decorative portion. 4.The method for manufacturing the pneumatic tire according to claim 1,wherein the at least one recess is a groove.
 5. The method formanufacturing the pneumatic tire according to claim 1, wherein the atleast one recess is a dimple.
 6. The method for manufacturing thepneumatic tire according to claim 1, wherein a depth of the at least onerecess is not less than 0.2 mm and not more than 2 mm.
 7. The method formanufacturing the pneumatic tire according to claim 1, wherein: the atleast one recess has an inclined face that inclines relative to a normalline direction of a tire surface, and a ratio of a length of thereflective material to a width of the inclined face of the recess isfrom 0.3 to 0.95.
 8. The method for manufacturing the pneumatic tireaccording to claim 1, wherein: the at least one recess has a bottomsurface parallel to a tire surface, and a ratio of a length of thereflective material to a width of the bottom surface of the recess isfrom 0.3 to 0.95.
 9. The method for manufacturing the pneumatic tireaccording to claim 1, further comprising a small protrusion that isprovided at a position above a maximum depth portion of the at least onerecess, protruding into the at least one recess.